QJsonObject partial path from variable - c++

Question

I have a json object that I load:
QJsonObject json = CommonToolkit::Types::LoadJson(config);
Here is a partial of the json file content:
{
"config": {
"macos": {
"screen": {
"main": {
"height": 0,
"left": 0,
"top": 0,
"width": 0
}
},
"windows: {
}
What I do is check what os i'm running in. Using the following variable to store that os:
QString osPath;
In my test osPath = "macos"
So I want to update the applications geometry
QJsonObject jparam{
{ "height", value.height() },
{ "left", value.left() },
{ "width", value.width() },
{ "top", value.top() }
};
My problem is when I try to set jon with jparam using osPath:
json["config"][osPath]["screen"]["main"] = jparam;
The error I'm getting is:
/Users/adviner/Projects/Notes/src/Notes/data/config.cpp:87: error: type 'QJsonValueRef' does not provide a subscript operator
json["config"][osPath]["screen"]["main"] = jparam;
~~~~~~~~~~~~~~^~~~~~~

Answer 1

Editing a Json in Qt is not a simple task, in this case when using json["config"] you get a QJsonValueRef, this class is a helper to get other types of elements like QJsonObject, QJsonArray, int, QString, etc. by what to get the next element must be used toObject() but this value is a copy, so if you modify it, the initial element will not be modified, you have to reassign it.
QJsonObject json = CommonToolkit::Types::LoadJson(config);
QString osPath = "macos";
QJsonObject jparam{
{ "height", value.height() },
{ "left", value.left() },
{ "width", value.width() },
{ "top", value.top() }
};
// get objects
QJsonObject config_obj = json["config"].toObject();
QJsonObject osPath_obj = config_obj[osPath].toObject();
QJsonObject screen_obj = osPath_obj["screen"].toObject();
// modify param
screen_obj["main"] = jparam;
// set objects
osPath_obj["screen"] = screen_obj;
config_obj[osPath] = osPath_obj;
json["config"] = config_obj;